Method and apparatus for injecting atomized fluids

Abstract

Methods and apparatus for injecting reagent, such as an aqueous urea solution, into an exhaust stream in order to reduce emissions from an engine exhaust. The present teachings can use a whirl plate having a plurality of whirl slots surrounding an exit orifice of an injector, which produce a high velocity rotating flow in the whirl chamber. When the rotating flow of reagent is passed through the exit orifice into an exhaust stream, atomization occurs from a combination of centrifugal force and shearing of the reagent by air as it jets into the exhaust stream.

1. An atomizing injector for injecting reagent, said atomizing injector comprising:
 an injector body having a reagent inlet, a reagent outlet, and a whirl chamber, said whirl chamber having an exit orifice; 
 a plurality of whirl slots being disposed in said whirl chamber for imparting a rotational velocity to reagent introduced into said whirl chamber; 
 a metering plug movably disposed within said injector body, said metering plug having a hollow pathway associated therewith in communication with said reagent inlet and said reagent outlet, said metering plug being movable between closed and opened positions; 
 a flow path for reagent through said injector body including said reagent inlet, said whirl chamber, said plurality of whirl slots, said hollow pathway, and said reagent outlet, said flow path permitting continuous cooling of said injector in both said closed and opened positions of said metering plug; and 
 a heat shield surrounding said exit orifice, said heat shield having an aperture therethrough aligned with said exit orifice, thereby allowing reagent released from said whirl chamber to pass through said heat shield. 
 
     
     
       2. The atomizing injector in accordance with  claim 1 , further comprising:
 means for introducing the reagent into said injector body; and 
 means for providing a predetermined pressure setpoint for pressurizing said reagent in said injector body; 
 wherein said metering plug meters a precise amount of said reagent having said rotational velocity from said exit orifice. 
 
     
     
       3. The atomizing injector according to  claim 2  wherein said predetermined pressure setpoint varies in response to operating conditions to provide at least one of increased operating range and varied spray patterns. 
     
     
       4. The atomizing injector in accordance with  claim 2  wherein said predetermined setpoint varies a droplet size of said reagent metered from said exit orifice. 
     
     
       5. The atomizing injector in accordance with  claim 4  wherein said droplet size is within a range of approximately 50 μm SMD or smaller. 
     
     
       6. The atomizing injector in accordance with  claim 2  wherein said predetermined setpoint varies a flow rate of said reagent metered from said exit orifice. 
     
     
       7. The atomizing injector in accordance with  claim 6  wherein said flow rate of said reagent metered from said exit orifice is in a range of approximately 1 to 600 grams per minute. 
     
     
       8. The atomizing injector according to  claim 1 , further comprising a biasing member biasing said metering plug into said closed position. 
     
     
       9. The atomizing injector according to  claim 8  wherein said biasing member comprises a coil spring coaxially disposed relative to said metering plug. 
     
     
       10. The atomizing injector according to  claim 8 , further comprising:
 an actuator actuating said metering plug between said closed and opened positions, said actuator having a magnetic coil generating a magnetic force, said magnetic force effecting a sliding motion of said metering plug against said biasing member when said magnetic coil is energized and thereby moving said metering plug from said closed position to said opened position within said whirl chamber to enable reagent to be released from said whirl chamber through said exit orifice. 
 
     
     
       11. The atomizing injector according to  claim 1  wherein said hollow pathway extends substantially through a length of said metering plug. 
     
     
       12. The atomizing injector according to  claim 11 , further comprising:
 a plurality of bores disposed in a first end of said metering plug proximate said whirl chamber, said plurality of bores being in communication with said hollow pathway; and 
 an outlet disposed in a second end of said metering plug, said outlet being in communication with said hollow pathway such that said flow path for reagent through, said injector body extends through said reagent inlet, said whirl chamber, said plurality of whirl slots, said plurality of bores, said hollow pathway, said outlet of said metering plug, and said reagent outlet independent of the position of said metering plug. 
 
     
     
       13. The atomizing injector according to  claim 1 , wherein said heat shield comprises:
 a plate surrounding said exit orifice; and 
 a layer of insulating material arranged on said plate. 
 
     
     
       14. The atomizing injector in accordance with  claim 1  wherein said whirl chamber comprises a removable whirl plate. 
     
     
       15. The atomizing injector according to  claim 1  wherein, in said open position, atomized reagent is dispensed from said exit orifice at a rate of approximately 1 to 600 grams per minute. 
     
     
       16. The atomizing injector according to  claim 1 , further comprising:
 a metering orifice in said reagent outlet for controlling the amount of the reagent flowing through said flow path. 
 
     
     
       17. The atomizing injector according to  claim 1 , further comprising:
 a plurality of cooling fins extending from said injector body. 
 
     
     
       18. The atomizing injector according to  claim 1  wherein at least one of said injector body and said metering plug comprises stainless steel. 
     
     
       19. The atomizing injector according to  claim 1  wherein at least one of said injector body and said metering plug comprises a thermoplastic. 
     
     
       20. The atomizing injector according to  claim 1  wherein, at least one of said injector body and said metering plug comprises a thermoset. 
     
     
       21. The atomizing injector according to  claim 1  wherein at least one of said injector body and said metering plug comprises a material compatible with urea. 
     
     
       22. The atomizing injector in accordance with  claim 1  wherein a pressure of the reagent in said injector body is in a range of approximately 60 to 150 pounds per square inch. 
     
     
       23. The atomizing injector in accordance with  claim 1  wherein said plurality of whirl slots comprises at least two whirl slots. 
     
     
       24. The atomizing injector in accordance with  claim 1  wherein said whirl slots are arranged transversely to a longitudinal axis of the metering plug. 
     
     
       25. The atomizing injector in accordance with  claim 1  wherein said reagent inlet is proximate the whirl chamber. 
     
     
       26. A method for injecting atomized reagent comprising:
 introducing a reagent into an injector body; 
 imparting a rotational velocity to said reagent by circulating said reagent through a whirl chamber disposed in said injector body, said whirl chamber having a plurality of whirl slots; 
 selectively actuating a metering plug disposed within the injector body between closed and open positions; 
 providing a flow path through the injector body, said flow path comprising a reagent inlet disposed in said injector body, said plurality of whirl slots, said whirl chamber, a hollow pathway associated with said metering plug, and a reagent outlet disposed in said injector body; 
 continuously circulating said reagent through said flow path, thereby enabling continuous cooling of said injector in both said open and closed positions of said metering plug; 
 metering atomized reagent from an exit orifice of the whirl chamber when said metering plug is in said open position; 
 providing a heat shield surrounding said exit orifice, said heat shield having an aperture therethrough aligned with said exit orifice; and 
 allowing reagent released from said whirl chamber to pass through said heat shield. 
 
     
     
       27. The method in accordance with  claim 26  wherein an amount of reagent circulated through said injector body for said cooling is greater than an amount of reagent metered from said exit orifice. 
     
     
       28. The method in accordance with  claim 26  wherein said reagent comprises a urea solution. 
     
     
       29. The method in accordance with  claim 26  wherein said reagent comprises a hydrocarbon. 
     
     
       30. The method in accordance with  claim 26  wherein said reagent comprises Alkyl Esters. 
     
     
       31. The method in accordance with  claim 26  wherein said reagent comprises alcohol. 
     
     
       32. The method in accordance with  claim 26  wherein said reagent comprises an organic compound. 
     
     
       33. The method in accordance with  claim 26  wherein said reagent comprises water.